Chain collisions, also known as “chain reaction crashes,” are series of front-to-rear collisions sometimes involving up to several hundred vehicles. Chain reaction crashes are characterized by each vehicle decelerating successively, an independent unit in an accelerating wave of compression which moves rearward down the column of following vehicles, Typically, all such vehicles are so close that it is nearly impossible for them to avoid colliding with the vehicle ahead, in which case we refer to them here as a chain. In the context of this invention, “chain reaction crash” refers to a series of collisions following from this accelerating wave of compression in a chain or column of hazardously close following vehicles.
Preventing rear-end collisions is a necessary concern. This is a simpler problem than preventing the multiple, simultaneous rear-end collision that is the chain reaction crash. Over the years various types of deceleration sensors/detectors have been used in one vehicle to activate rearwardly facing lights in that one vehicle.
Deceleration detection techniques have been proposed in numerous prior art references. See for example, U.S. Pat. Nos. 5,821,851 to Blackmer; 3,593,278 to Bower; 3,638,181 to Bryant; 3,665,391 to Bumpous; 5,461,362 to Echt; 3,760,353 to Hassinger; 3,846,748 to Hopwood; 4,920,330 to Plozner, and 5,089,805 to Salsman. These patents generally use deceleration indicators to actuate rear brake lights.
All of the above patent references generally employ mercury switche, with the exception of U.S. Pat. No. 5,821,851 to Blackmer. Mercury is undesirable since it is the subject of a U.S. environmental initiative and is recognized worldwide as a dangerous environmental pollutant, and mercury is considered to be toxic even if not ingest. Only U.S. Pat. No. 3,593,278 to Bower allows for the possibility of closing internal electrical contacts with a fluid other than mercury. No information on such a fluid is provided. U.S. Pat. No. 3,846,748 to Hopwood and U.S. Pat. No. 5,089,805 to Salsman use multiple mercury switches which worsen the hazards.
As U.S. Pat. No. 3,665,391 to Bumpous notes, existing brake lights are barely visible in the daytime because of their low candlepower. Nevertheless, all the above U.S. Patents use existing brake lights to provide warnings to other vehicles, illuminating them by brake pedal action as well as by means of deceleration detection. To correct the problem of brake lights being insufficiently visible in daylight, the Bumpous patent employs the vehicle's horn to warn of sudden stops. However, it is doubtful that a following vehicle would hear the horn of a vehicle ahead.
Generally, the deceleration indicators described in the above patent references are complicated and expensive. See for examples U.S. Pat. Nos. 5,821,851 to Blackmer; 3,638,181 to Bryant; 3,846,748 to Hopwood; 4,920,330 to Plozner; and 5,089,805 to Salsman. Expensive complicated techniques are clearly undesirable.
Several devices in the prior art rely only on deceleration detection to alter standard brake light display. See for example, U.S. Pat. Nos. 5,461,362 to Echt and 3,760,353 to Hassinger. The Echt's device causes a vehicle's brake lights to flash in response to a pre-set amount of “panic braking.” However, flashing brake lights universally indicate that a vehicle is proceeding slowly, not stopping, so this is misleading. Hassinger's device causes brake lights to flash continuously once deceleration reaches a pre-set point. This has the same defect as Echt's patent, namely, the flashing brake lights only indicate that a vehicle is going slowly, not decelerating. Therefore, neither Hassinger's nor Echt's devices would be effective to ward off overtaking vehicles. Hassinger's device also uses an emergency stop light that must be manually reset switch after every deceleration.
U.S. Pat. Nos. 5,821,851 to Blackmer and 3,760,353 to Hassinger discuss the problem that brake lights can illuminate at any contact of the brake pedal, no matter how slight. Blackmer also notes that when slowing and stopping are accomplished by manual transmission downshifting, the brake light is not illuminated i.e., the brake light is not displayed when the transmission is used to slow the vehicle. This can be important because manual transmissions are so used in cars and trucks around the world.
Manual transmissions slow vehicles through use of a supposed “engine brake” applied through the transmission gears. Like Hassinger, Blackmer also notes that brake lights do not indicate whether the brake pedal has been applied with sufficient pressure to be effective. Although Blackmer notes automobiles may slow and stop by downshifting, this reference neglects to discuss the problem of trucks, where downshifting is essential, the almost universal means of braking. Large trucks must practically always be slowed by downshifting, double-clutching, or by use of a variant engine brake, the Jacobs Vehicle System, “Jake Brakes.”
Large trucks also use air brakes. Air brakes use a compressor on the truck motor to pressurize a tank. Once pressurized, air from the tank forces the trailer's powerful steel spring brakes off the brake drums, allowing the trailer wheels to turn freely. An operator is able to slow and stop by reducing air pressure in the tank, which allows the springs to compress brake shoes around brake drums. But brake shoes wear rapidly and on downward grades they can “fade” and become ineffective. Additionally, frequent adjustment of the brake shoes is required.
Despite warnings posted on the rear of trucks indicating they have air brakes, automobile drivers rarely understand that trucks with air brakes can stop extremely rapidly, sometimes altogether out of the truck operator's control. This occurs when, for one reason or another, the air brake system loses pressure. This allows its spring brakes to lock up tight. Evidence of this can be seen on almost any highway where heavy brake marks, often diagonally crossing traffic lanes, indicate that trucks have suddenly been braked to a stop. Because of the danger that automobiles will collide with the rear ends of trucks, often sliding beneath them in the process, either because of this drastic braking or because of involvement in a conventional chain reaction collision. The Federal Motor Carrier Safety Regulation (Sect. 393.86) requires truck trailers to have a “rear end protection” bumper, the “ICC bar,” and rear-end signs stating, “Warning—Air Brakes.”
Another major danger is uncontrolled deceleration from air brakes. Collisions can also result from trucks following other trucks closely in order to save fuel. The vacuum or “draft” behind a truck ahead helps “pull” closely following, “drafting,” trucks along.
Another problem is the flicker light effects. Brake lights tend to flicker on and off at the slightest foot-to-pedal contact. The lights are not consistently associated with speed reductions and consequently are largely ignored.
Chair collisions involve additional factors, especially the obscuring presence of other vehicles, perhaps many other vehicles, further ahead. Above prior art patents assume rear brake lights will be seen in time to prevent collisions. But only the operator of the vehicle immediately following can see them, even if displayed in timely fashion, since vehicles further ahead are obscured by those behind them. This is especially the case with large trucks, which entirely obscure vision ahead. Thus, the operators of vehicles forming chains, that is, traveling in dangerously close proximity, are usually ignorant of what is developing ahead of them, even in clear weather.
The exclusive concern of the prior art patents cited above is prevention of a single rear-end collision of a motor vehicles and truck. However, this is a much simpler problem than chain collisions. A rear-end collision involves only two (2) vehicles, one striking the other from the rear, which represents a simple error in judgment on the part of one vehicle operator. On the other hand, a chain collision or “chain reaction crash” refers to the involvement of a multiplicity of vehicles in a multiplicity of collisions, occurring almost simultaneously, and resulting from an accelerating wave of compression moving rearward along a column of vehicles and meeting the vehicles as they move forward. This occurs so swiftly that it cannot be explained in terms of individual error of judgment. It might better be termed a social accident, especially since its consequences can be societal.
Chain collisions are a worldwide problem for vehicles of all types, including taxying or flying aircraft, vessels on, over, or under the water, and solid terrain vehicles. They frequently involve hundreds of vehicles and, world-wide, are extremely costly in lives lost, injuries, and money.
None of the prior art reference singularly or in combination overcome the problems presented above of reducing and preventing plural vehicle chain collisions. Thus, the need exists for solutions to these problems.